(a) Field
The subject matter disclosed generally relates to complex structure containing carboxyl substituted starch and lipid for delayed delivery of drugs, including medications used to treat the symptoms of Crohn's disease.
(b) Related Prior Art
Crohn's disease, also known as regional enteritis, is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract, causing a wide variety of symptoms. It primarily causes abdominal pain, diarrhea (which may be bloody if inflammation is at its worst), vomiting (can be continuous), or weight loss, but may also cause complications outside the gastrointestinal tract such as skin rashes, arthritis, inflammation of the eye, tiredness, and lack of concentration. Crohn's disease is caused by interactions between environmental, immunological and bacterial factors in genetically susceptible individuals. This results in a chronic inflammatory disorder, in which the body's immune system attacks the gastrointestinal tract possibly directed at microbial antigens. Crohn's disease has traditionally been described as an autoimmune disease, but recent investigators have described it as a disease of immune deficiency.
There is no known pharmaceutical or surgical cure for Crohn's disease. Treatment options are restricted to controlling symptoms, maintaining remission, and preventing relapse. Acute treatment uses medications to treat any infection (normally antibiotics) and to reduce inflammation (normally aminosalicylate anti-inflammatory drugs and corticosteroids). When symptoms are in remission, treatment enters maintenance, with a goal of avoiding the recurrence of symptoms. Prolonged use of corticosteroids has significant side-effects; as a result, they are, in general, not used for long-term treatment. Alternatives include aminosalicylates alone, though only a minority are able to maintain the treatment, and many require immunosuppressive drugs. On the other hand, it has been also suggested that antibiotics change the enteric flora, and their continuous use may pose the risk of overgrowth with pathogens such as Clostridium difficile. 
Medications currently used to treat the symptoms of Crohn's disease include 5-aminosalicylic acid (5-ASA) formulations (Mesalamine), prednisone, immunomodulators such as azathioprine, mercaptopurine, methotrexate, infliximab, adalimumab, certolizumab and natalizumab. Hydrocortisone should be used in severe attacks of Crohn's disease.
Medications to treat the symptoms of Crohn's disease have to be in a dosage form with a timed delivery (chrono-delivery) to occur in the colon area of the GI tract. There are numerous problems with this chrono-delivery of the medications, i) pH in the colon area is around 7 and ii) the dosage form must be coated to prevent dissolution in the stomach.
It is highly desirable to have a dosage form for delivery of a medication in the colon, wherein the dosage form is simple to produce, is pH independent and has a high drug load.